1. Field of the Invention
The present invention relates to a vehicle diagnosis system and a vehicle diagnosis apparatus, which can diagnose a vehicle.
2. Description of Related Art
A conventional vehicle diagnosis system in an electronic control unit (engine ECU) mounted on a vehicle stores a diagnosis code corresponding to a detected trouble in a backup RAM, and informs a trouble occurrence to user by lighting a warning lamp such as a check engine lamp. This system is equivalent to OBD(California On Board Diagnosis) II. In the case of a vehicle which mounts the OBD II system, several ECUs mounted on the vehicle are connected to an external scan tool via a K-line in a repair shop. The external scan tool communicates with the ECUs by IS09141 protocol using a communication format decided by SAE, and reads the diagnosis code to diagnose a trouble.
Recently, CARB (California Air Resource Bureau) requests that the diagnosis system have a radio transponder so that it can reply for requests by using a radio communication (i.e., OBD III).
Several vehicle diagnosis systems have proposed to communicate the diagnosis data by using the radio communication. For example, in a vehicle diagnosis system, as described in Japanese Laid-open Patent No.5-332888, a trouble message including trouble data from each engine ECU and predetermined identified code is sent as a radio signal using a weak radio wave. Receiving stations provided in some areas receive the trouble message each of which is sent from vehicles in the area, and send the received trouble message to a terminal unit in a repair shop via a telephone line. Then, the terminal unit can identify a user and detect trouble contents of user's vehicle.
In a vehicle diagnosis system, as described in Japanese Laid-open Patent No. 7-50886, an FM radio diagnosis device receives an FM radio signal from an external diagnosis device provided in a repair shop or the like, and then send command data related to the FM radio signal to each engine ECU mounted on the vehicle. When each engine ECU sends a response, the FM radio diagnosis device takes out diagnosis data from the response and sends an FM radio signal related to the taken-out diagnosis data to the external diagnosis device.
Further, in a vehicle diagnosis system, as described in Japanese Laid-open Patent No. 3-4660, a measuring device is connected to engine ECU mounted on the vehicle. The measuring device has a radio communication portion for sending and receiving a radio signal. The measuring device connects the engine ECU to an external control center via an automobile telephone network by using the radio communication portion. When a diagnosis instruction is input to an input control terminal of the measuring device, vehicle diagnosis data is output from the engine ECU. Then the vehicle diagnosis data is sent to the external control center to diagnose the diagnosis data. Finally, a result of the diagnosis is returned to the radio communication portion of the measuring device.
Here, when there are not many radio wave monitor stations, it is desired to diagnose the vehicle by using the external scan tool. However, none of the above-mentioned conventional vehicle diagnosis system meets this desire.
Further, even if there are many radio wave monitor stations, it may take long time for many vehicles to have diagnosis system equivalent to OBD III, if such a diagnosis system is newly developed.